Microwave It!

If you think about it, microwave ovens are pretty powerful tools for scientific investigation. Electromagnetic waves of a specific frequency are sent back and forth through a contained box. You can control time and the energy of the waves, and observe how they react with a variety of materials.

If you’ve got a microwave oven handy (and permission from
your grown up to use it), here are a couple of investigations to try out.

Speed of Light

Did you know you can measure the
speed of light with a large chocolate bar, a ruler, calculator, and a microwave
oven? Microwaves are after all just
light waves with a wavelength too big for our eyes to see. Here’s how you
measure their speed.

First, if your microwave has a
rotating plate, remove or disable the plate and all the parts that spin it
around. You don’t want anything to move
in the microwave when it is on.

Next place the chocolate bar upside
down on a paper plate so that the nice smooth chocolaty surface is facing up.

Put the plate in the microwave and
heat it on high for 15 seconds.

Remove the plate and look for the
melted spots on the chocolate. Use the
ruler to measure the distance between the close edges of two melted spots in
centimeters. These two spots are where
the light wave went into the chocolate bar and came back out again and is equal
to half of a microwave wavelength

Use your calculator to divide that
distance by 100. This is the distance in
meters. Multiply that number by 2 to get
the full wavelength in meters.

Look on the door or back of your
microwave to find the frequency of the light waves it uses to cook your
food. Most microwaves have a frequency
of 2450 MHz, which are 2,450,000,000 waves per second!

Multiply the full wavelength in
meters by 2,450,000,000 waves/second to get the speed of light. You should get something close to 300,000,000
meters/second!

And if chocolate (and the metric system) is not your thing you can use Peeps instead

Speaking of Peeps….

Peeps (or
Marshmallows)

It used to be that you could only
find Peeps at Easter time but now there are Peeps for every major holiday –
even Thanksgiving. But if you can’t find them right now you can
always just use regular marshmallows.

Place a few Peeps on a paper plate
– it will make a sticky mess.

Microwave the Peeps for 1
minute. When do they start to puff
up? Do they keep getting bigger for the
whole minute?

Take the Peeps out of the microwave
and dissect one with some toothpicks (it’s hot and you don’t want to burn your
fingers). Is it hollow inside? Measure the Peeps before and after to see how
many times bigger the microwaved peep grew.
What happens to the shape, size and appearance of the Peeps as they cool
down?

Peeps are made of sugar, water and
air. In the oven, the microwaves heat up
the water (which also heat up the air and sugar) until it turns to steam and
pushes against the warm soft sugar, making bigger bubbles inside the Peep and
causing it to grow in size. When it cools
down the bubble shrink back down and so does the Peep.

Does it matter if you use fresh or
stale Peeps? Turn microwaving Peeps into
a game with Peep
Jousting! Also check out this peek
inside a Peep factory. What happens
when you microwave other candies?

Ivory Soap

Not all soaps are created
equal. Ivory soap was once marketed as
“The soap the floats!” This is because
Ivory soap has bubbles whipped into it.
If you look carefully at the bar of soap you will notice tiny bubbles
all over its surface. This causes an
interesting change in the soap when you microwave it.

Place the soap on a paper plate and
microwave it on high for 1 minute. What
happens to the soap? It should transform
from a rectangular bar into something that resembles a fluffy white cloud.

When you cook ivory soap in the
microwave, two things happen. The soap
itself becomes soft and the air and moisture trapped in those bubbles heats up
and expands very quickly in the soft soap making a beautiful cloud-like foam.

What happens if you microwave other
bars of soap? Does the same thing happen
if you put the plate of Ivory soap in a hot oven?

Grapes & Boiled
eggs

The folks at the New York Times
investigated what happens when you microwave
boiled eggs (a loud explosion!) and grapes
(a glowing plasma)

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